Underworld don David Billa (Ajith Kumar); is on Interpol's criminal list; hiding and operating out of Malaysia.DSP Jayprakash (Prabhu Ganesan) has spent the last few years looking for Billa; leaving behind a life in India.During a chase with the police Billa is severely wounded after an accident and dies in front of the DSP. The DSP realises that keeping Billa's death as a secret is the best way to inflitrate the gang. He tracks down a look-alike called Saravana Velu (Ajith Kumar); a lowly pick-pocket and asks Velu to infiltrate Billa's gang by pretending to be Billa. Velu does so; but in a encounter; the DSP is killed. Now Velu gets arrested and none believes that he is not the real Billa. Velu now has to break the law and escape to prove his innocence.